Conventionally, there are commonly well-known music reproduction apparatuses, which employ portable media players (hereinafter appropriately abbreviated as the PMPs) as removable external audio sources, and which are capable of downloading and reproducing desired music (for example, see Patent Literature 1). It is to be noted that, in the present specification, the “portable media players” are not limited to those dedicated to downloading music, but include devices with the mobile phone function which are capable of connecting to a communication line of the Internet or the like, and are capable of downloading music via the communication line. Further, in the present specification, the “external audio sources” refer to audio sources or music media such as the aforementioned portable media players or compact discs, which can be attached to and removed from the music reproduction apparatuses.
Further, there are other known music reproduction apparatuses, which employ two types of audio sources, i.e., the portable media player and the compact disc (hereinafter appropriately abbreviated as the CD), each as the removable external audio sources, so that one of the audio sources can be selectively used for music reproduction. Such apparatuses are partially already in use.
Still further, in connection with such music reproduction apparatuses capable of addressing reproduction of two different types of external audio sources, there is known one in which a CD-use reproduction unit having a CD retaining mechanism capable of retaining a CD and a PMP-use reproduction unit having a PMP retaining mechanism capable of retaining a PMP are arranged next to each other, and an opening-closing door that covers at least one of the reproduction units in an openable and closable manner is provided.